Revit Systems is an interesting product. I believe it's ready when it comes to mechanical systems, but it could use more hardware when it comes to electrical and it's plumbing features are new. It will be an excellent product in another year or two (its excellent in capabilities currently). But its still in its early years and developing content so currently I tell people that its a good product, but Autodesk Building Systems is likely the better product at the moment. BUT 1-2 years from now Revit Systems will be far and away the program to go to and use.
In short: Don't be afraid of it, it can work well for you. But it's still a young program and it's rapidly improving and gaining features so it's possible that TODAY (depending on what you do and your architectural design program) ABS (Autodesk Building Systems) may be a better fit for you.
EDIT: I notice you currently use ABS and ADT... that being said, I'd likely stick with ABS for another year then make the move unless you are working with others that use Revit extensively.
